One of the illumination devices is an organic electroluminescent lighting device that uses, as a light source, a light-emitting element including an organic light-emitting film held between a pair of electrode films different from each other in polarity. In the organic electroluminescent lighting device, the organic light-emitting film emits light when an electric field is generated between the pair of electrode films. The light of the organic light-emitting film is transmitted through one of the electrode films to be applied to the outside. Accordingly, one of the electrode films is made of a transparent metallic material such as ITO (indium tin oxide), ZnO, or SnO2 (NESA glass).
However, the aforementioned transparent metallic material has relatively high resistance. Further, in the electrode film, generally, each of the opposite edge sides of its surface is a power supply terminal. Thus, in the electrode film, wiring resistance increases farther away from each edge side. The increase of the wiring resistance is accompanied by the increase of a descending voltage. This disables uniform application of a voltage to the entire organic light-emitting film. The brightness of the organic light-emitting film depends on the voltage. Thus, when the voltage is not uniformly applied to the organic light-emitting film, there is a possibility that the brightness of the organic light-emitting film is not uniform.
Patent Literature 1 (JP2004-14128A) has therefore disclosed an organic electroluminescent lighting device for preventing the occurrence of the brightness nonuniformity of the organic light-emitting film. The organic electroluminescent lighting device disclosed in Patent Literature 1 includes auxiliary electrodes made of materials having a lower resistance than a transparent electrode and arranged on a grid pattern in the surface of the transparent electrode. According to this organic electroluminescent lighting device, the resistance value of the entire transparent electrode is reduced by forming, in the transparent electrode, auxiliary electrodes that have a lower resistance than the transparent electrode. The wiring resistance accordingly drops to reduce the value of the descending voltage. As a result, the brightness nonuniformity of the organic light-emitting film can be prevented.